You could ask why do we differentiate between women and men or different skin colours; it's simply because they are physically different. The discrimination comes from what people infer by that differentiation.

The term "gay" has been misused for a long time so it has a derogatory association but it's the misuse of the term that's to blame and not the act of differetiation.

It's not discrimination to differentiate. Homosexual couples haven't evolved to conceive through sexual interaction so the relationship is defined differently from a heterosexual couple.
Hetero = different, homo = the same. Heterosexual couple = different gender, homosexual couple = same gender.
You could ask why do we differentiate between women and men or different skin colours; it's simply because they are physically different. The discrimination comes from what people infer by that differentiation.
The term "gay" has been misused for a long time so it has a derogatory association but it's the misuse of the term that's to blame and not the act of differetiation.

Steven Fry apparently asked Steve Jobs if the Apple logo was a tribute to Alan Turing and he replied “It isn't true, but God we wish it were!”.

Given that these events happened such a short time ago, it will take time for some terms describing homosexuality to have a positive association. It may never happen entirely as it's still illegal in parts of the world and was only made legal recently in a lot of places:

It's probably got something to do with homosexuality being illegal around 50 years ago. One high profile victim was Alan Turing (father of computing) who was convicted of homosexuality in the 1950s:http://ibnlive.in.com/news/alan-turing-committed-suicide-after-chemical-castration-for-homosexuality/267468-11.html
He was given hormone treatment and lost his job so he committed suicide by eating an Apple laced with cyanide. The UK government made a symbolic public apology a few years ago for the treatment:http://news.bbc.co.uk/1/hi/8249792.stm
Steven Fry apparently asked Steve Jobs if the Apple logo was a tribute to Alan Turing and he replied “It isn't true, but God we wish it were!”.
Given that these events happened such a short time ago, it will take time for some terms describing homosexuality to have a positive association. It may never happen entirely as it's still illegal in parts of the world and was only made legal recently in a lot of places:http://en.wikipedia.org/wiki/LGBT_rights_by_country_or_territory
Religion plays a strong role in attitudes towards homosexuality and in many cases those ideologies are designed to be unchanging.

You know what bogles my mind? the fact that "Christians" are taught to love yet they tell gays they are doing a sin WTF?

Why differentiate people with a label based on there sexual orientation? Are they not also human? Why is there even discrimination against these people?

Discuss.

People need labels, categories, classes, cultures and subcultures to understand those different from us. It has been so since the dawn of existence. But of course now with the Age of Aquarius upon us we are recognising universal love.

That said, pure non-dualism recognises and celebrates differences to.

So on one hand we should celebrate differences, on the other, seek universal, common values/love.